Track lock



Dec. 30, 1941. E. s. PRINGLE ET AL TRACK LOCK Filed Aug. 1, 1940 2 Sheets-Sheet 1 @Q Q m 59% RD. mm Y N & WS mw a 0 mm EC Y M B omv r ATTORNEYS 1941- E. s. PRINGLE ET AL 2,2 02

TRACK LOCK Filed Aug. 1, 1940 2 Sheeis-Sheetfi,

Flip-4+ mwarasf'i fififii ea BY CarlosEharrmgTon, 3 @w gwzw (5% ATTORNEYS Patented Dec. 30, 1941 UNITED STATES PATENT OFFICE TRACK LOCK Application August 1, 1940, Serial No. 349,270

3 Claims.

Our invention relates in general to locking means, and particularly to locking means applicable to hoist trolleys.

It is well known to those skilled in the art that in a device of this type it is necessary that the lock means carried by the trolley exert a clamping action upon the track which is in proportion to the load carried by the hoist.

The principal object of our invention has been to provide a track lock which shall meet the above requirements as to clamping action.

Another object has been to provide a track lock which may be operated by means of a hand chain, thereby making it possible to operate the device from any position or at any distance from the hoist.

Another object has been to provide such a lock with clamping means so designed as to compensate for wear and variation in the size of the track, and one which will not injure the track.

Moreover, it has been an object of our inven-- tion to provide a device which will lock on either curved or straight track but which, when released, will not interfere with the operation of the trolley around curves.

Furthermore, our device is so designed that the lock itself bears the clamping action without imposing any additional load upon the wheels, bearings or frame of the trolley.

Moreover, our device, when used with a track of I-beam cross section, is so designed that it engages with such portions of the track that splice plates may be used on either the web or bottom flanges of the I-beam.

The above objects and advantages have been accomplished by the device shown in the accompanying drawings, of which:

Fig. 1 is a side elevation of our complete device.

Fig, 2 is an end elevation of the same.

Fig. 3 is a sectional plan view taken on line 33 of Fig. 2.

Fig. 4 is a perspective view of one of the lock brackets.

Fig. 5 is a perspective view of a modified form of lock unit.

Fig. 6 is a side elevation of a modified form of lock screw.

It is Well known to those skilled in the art that hoist trolleys are usually mounted on tracks formed of structural steel of I-beam cross section, and the track In shown in the drawings is of this cross section having a web H, an upper flange l2, and a lower flange l3.

The trolley is formed preferably of side plates I4 and I5 upon each of which is mounted two trolley wheels l6. These trolley wheels preferably have cylindrical peripheries and each is provided with a flange I! which bears against the side edge 20 of the I-beam flange l3 and thereby centralizes the trolley. Each of the trolley wheels is preferably carried upon a stud 21 which is securely fastened to the side plates 14 and 15 of the hoist. These side plates are inclined inwardly at their bottoms so that the axes of the studs 2| are preferably parallel with the top surfaces of the flange [3 of the I-beam. The trolley side plates are held together at their lower ends in customary manner by means of a hoist bar pin 22 which passes through the plates and upon which a hoist bar 24 is mounted, suitable spacers 23 being disposed upon the pin on each side of the bar.

Our lock is carried by two lock brackets 25 and 26, secured respectively to the side plates I4 and I5 of the hoist by means of the rivets shown or by any other suitable means. Each of these bracket comprises a base plate by which it is secured to the side plate and with an offset bearing portion 3|. The bearing portions extend forwardly beyond the forward edges of the plates 14 and I5 and each is provided with a bearing 32 for the lock screw 34 and with a bearing 35 for engagement with the lock shaft 36. The ends 33 and of the lock screw are preferably reduced in diameter where they are mounted within the bearings 32 and the screw is therefore prevented from endwise motion when assembled within the brackets. The lock shaft 36 is arranged preferably below the lock screw 34 and is held in place within its bearings 35 by means of cotter pins 4|. In the preferred form of lock screw 34 right-hand screwthreads 44 are provided at one side and left-hand screwthreads at the opposite side.

Carried by the lock screw and the lock shaft are the lock units 42 and 43 of our device. The lock unit 42 is mounted upon the left-hand screw-threads 45 of the screw and is therefore provided with a left-hand screwthreaded aperture 46. In like manner, the lock unit 43 is mounted upon the right-handed screwthreads 44 and therefore its aperture is formed with screwthreads of the same hand. Obviously, by this arrangement, rotation of the screw in one direction will draw the lock units toward each other and will force them away from each other by reverse rotation.

On the outer reduced end 40 of the lock screw there is provided a lock chain hand wheel 5|.

over which a chain 52 passes, whereby the screw may be rotated. A guard 51 carried by the bracket 25 extends across the wheel so as to retain the chain in position. The lower end of each lock unit is preferably widened by the provision of a projection 53, and an aperture 54 is formed through this part of each of the units which are so spaced with relation to the screwthreaded apertures 45 and 58 that they will engage with the lock shaft 365. units with the lock shaft keeps the lock units in alignment upon the screw 34 and also provides bearings on said shaft of sufficient length to substantially counteract the bending tendency of the lock units. Each of the lock units is formed in its inner face at a point opposite the surface with a groove 55 designed to fit the lower surface of I-Joeam flange l3 and the upper tapered surface thereof, whereby a wedging action is produced when the units are locked upon the track. Due to the wedging action, our lock may be so designed as to resist a horizontal pull on the trolley which is equal to a large proportion of the load sustained by the hoist carried thereby. Since these grooves are tapered, they will compensate for any wear occurring either upon the flange or in the groove of the lock unit.

In Fig. 5 I have shown a modified form of lock unit 63 which is particularly applicable to trolleys designed to pass overa track which is curved or inclined in a vertical plane. This unit has an upstanding clamping end which is formed with a straight-walled surface (if for engagement of the edges of the I-beam. This lock unit is provided with suitable screwthreads 62 for engagement with the screw 3:! and with an aperture 63 for sliding engagement with the lock shaft 35.

From the foregoing itwill be obvious that when the wheel 5| is rotated by means of the chain 52,

the lock screw 34 will also be rotated. In one direction of rotation the lock units 42 and 43 will be drawn toward each other because of the right and left-hand threads formed on the screw. As these lock units are drawn toward each other the groove 55 formed in each of them will engage the adjacent edge of the flange [3 and, due to the tapered formation of the grooves 55, will be crowded onto the flange in looking engagement therewith without adding any load to the trolley. t will be clear that the pitch of the threads 44 and 45 and the diameter of the wheel 5| may be made such as to produce substantially any pressure desired within the required limitation. Obviously, when the wheel 5| is rotated in the opposite direction, the lock units will be separated from each other and will be cleared from clamping engagement with the I-beam. As the locking units are moved along the screw 34, obviously the lower ends of these units will be guided in their movement by the shaft 36.

In Fig. 6 I have shown another modification. In this figure the screw 64 is provided with two screwthreaded portions and 65, preferably of different diameters. The portion 65 is provided with screwthreads of finer pitch than the portion 66 thereof, although the screwthreads on both Engagement of the portions are of the same hand. This will cause the lock units (not shown) to move in the same direction when clamping action is desired but at a different ratio so that a differential action is produced. There is in the trolley suificient side play to compensate for this unsymmetrical movement of the lock units. When being assembled, the lock units may be placed upon the structure in such position that the parts will come together in final locking position when the hoist is substantially in its normal central position.

Obviously, some modifications of the details herein shown and described may be made without departing from the spirit of our invention or the scope of the appended claims, and we do not, therefore, wish to be limited to the exact embodiment herein shown and described, the form shown being merely a preferred embodiment thereof.

Having thus described our invention, what we claim is:

1. The combination with a track, of a trolley frame adapted to be supported thereby, a lock bracket carried at each side of said frame, a lock screw rotatably carried by said brackets and held against axial movement therewith, a single lock shaft carried by said brackets, said lock shaft being in interspaced parallel arrangement with said screw and having its axis in substantially the same vertical plane as the axis of said screw, and lock units slidably mounted upon said shaft and having screwthreaded engagement with said screw to draw said units into clamping engagement with said track.

2. The combination with a track, of a trolley frame formed of interspaced plates and adapted to be supported by said track, a lock bracket secured to each plate and disposed at each side of said frame, a lock screw rotatably carried by said brackets and held against axial movement therewith, a single lock shaft carried by said brackets, said lock shaft being in interspaced parallel arrangement with said screw and having its axis in substantially the same vertical plane as the axis of said screw, and lock units slidably mounted 1 upon said shaft and having screwthreaded engagement with said screw, each of said lock units having a clamping surface engageable with opposite sides of said track, said surfaces being substantially in alignment with a plane passing through the axes of said screw and said shaft.

3. The combination with a track, of a trolley frame formed of interspaced plates and adapted to be supported by said track, a lock bracket secured to each plate and disposed at each side of said frame, a lock screw rotatably carried by said brackets and having its axis disposed in a horizontal plane, a single lock shaft carried by said brackets, said lock shaft being in interspaced parallel arrangement with said screw and having its axis in substantially the same vertical plane as the axis of said screw, lock units slidably mounted upon said shaft and having screwthreaded engagement with said screw, a chain wheel carried by said lock screw, and a hand chain suspended from said wheel for operating said screw.

EDWARD S. PRINGLE. CARLOS E. HARRINGTON. 

